The low-hanging fruit: the refinery was recently retooled as part of its “modernization project,” which will “provide Whiting with the capability of processing up to about 85% heavy crude, versus about 20% today.”

Albeit, “heavy crude” is produced in places other than Alberta's tar sands, with Venezuela serving as the world's other tar sands-producing epicenter. So, in theory, if it's heavy crude that spilled into Lake Michigan, it could be from Venezuela.

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